Plate-like alumina particles, method for producing plate-like alumina particles, and resin composition

Abstract

Plate-like alumina particles have an aspect ratio of 5 to 500, in which in solid-state 27 Al NMR analysis, the longitudinal relaxation time T 1 for a peak of six-coordinated aluminum at 10 to 30 ppm is 5 seconds or more at a static magnetic field strength of 14.1 T.

1 . Plate-like alumina particles characterized by having an aspect ratio of 5 to 500,
 wherein in solid-state  27 Al NMR analysis, a longitudinal relaxation time T 1  for a peak of six-coordinated aluminum at 10 to 30 ppm is 5 seconds or more at a static magnetic field strength of 14.1 T.   
     
     
         2 . The plate-like alumina particles according to  claim 1 , further comprising silicon and/or germanium. 
     
     
         3 . The plate-like alumina particles according to  claim 1 , further comprising molybdenum. 
     
     
         4 . The plate-like alumina particles according to  claim 3 , wherein the plate-like alumina particles have a molybdenum content of 0.1% or more and 1% or less by mass in terms of molybdenum trioxide based on 100% by mass of the total mass of the plate-like alumina particles. 
     
     
         5 . The plate-like alumina particles according to  claim 1 , wherein the plate-like alumina particles have a thickness of 0.01 to 5 μm and an average particle size of 0.1 to 500 μm. 
     
     
         6 . The plate-like alumina particles according to  claim 1 , wherein the plate-like alumina particles have an average particle size of 0.1 to 7 μm. 
     
     
         7 . A method for producing plate-like alumina particles according to  claim 1 , comprising mixing an aluminum element-containing aluminum compound, a molybdenum element-containing molybdenum compound, and a shape-controlling agent together to prepare a mixture, and firing the mixture at 1,200° C. or higher. 
     
     
         8 . The method for producing plate-like alumina particles according to  claim 7 , wherein the shape-controlling agent is at least one selected from the group consisting of silicon, silicon compounds, and germanium compounds. 
     
     
         9 . The method for producing plate-like alumina particles according to  claim 8 , wherein 50% or more by mass of the aluminum element-containing aluminum compound in terms of Al 2 O 3 , 2% or more by mass and 15% or less by mass of the molybdenum element-containing molybdenum compound in terms of MoO 3 , and 0.1% or more by mass and 10% or less by mass of the shape-controlling agent in terms of SiO 2  or GeO 2  based on 100% by mass of the total amount of the raw materials on an oxide basis are mixed together to prepare a mixture, and the mixture is fired. 
     
     
         10 . A resin composition, comprising a resin and the plate-like alumina particles according to  claim 1 . 
     
     
         11 . The plate-like alumina particles according to  claim 1 , further comprising silicon and/or germanium; and molybdenum. 
     
     
         12 . The plate-like alumina particles according to  claim 11 , wherein the plate-like alumina particles have a molybdenum content of 0.1% or more and 1% or less by mass in terms of molybdenum trioxide based on 100% by mass of the total mass of the plate-like alumina particles. 
     
     
         13 . The plate-like alumina particles according to  claim 1 , wherein the plate-like alumina particles have a thickness of 0.01 to 5 μm and an average particle size of 0.1 to 500 μm, and the plate-like alumina particles have an average particle size of 0.1 to 7 μm.